Biomedical subjects
Publications and source records attributed to John R Baker.
Synthetic peptides corresponding to portions of group B streptococcal peptidoglycan were used to show that the endopeptidase activity of bacteriophage B30 lysin cleaves between D-Ala in the stem peptide and L-Ala in the cross bridge and that the minimal peptide sequence cleaved is DL-gamma-Glu-Lys-D-Ala-Ala-Ala. The only glycosidase activity present is that of N-acetyl-beta-D-muramidase.
The use of psychedelic substances within a context that emphasizes religious experiences and aims to provide spiritual insights is not a new phenomenon. However, the proscription of these substances in most modern societies leads to such use now typically occurring in an underground and idiosyncratic manner that often leaves individuals on their own with regard to the interpretation and integration of their experiences and insights. In contrast, the numerous examples in the ethnographic and the historical literature indicate that many cultures independently developed similar frameworks for using these substances for both individually and socially beneficial purposes and arrived at similar conclusions as to which of the substances available to them were the most appropriate for these purposes. This article focuses on a special type of socially sanctioned framework called a "sacrament" and contrasts this with other, more idiosyncratic forms of psychedelic use. It discusses how this framework helps to structure and channel the experiences induced by these substances, thereby increasing the likelihood of individually constructive and socially integrative experiences.
To investigate possible relationships between polychlorinated biphenyl (PCB) exposure and infectious disease mortality in harbor porpoises (Phocoena phocoena) in United Kingdom waters, summed blubber concentrations of 25 chlorobiphenyl congeners (sigma25CB) in healthy harbor porpoises that died of acute physical trauma (mainly by-catch; n = 175) were compared with sigma25CB values in animals that died of infectious disease (n = 82). The infectious disease group had significantly greater sigma25CB values (mean, 27.6 mg/kg lipid) than the physical trauma group (mean, 13.6 mg/kg lipid; p < 0.001). This association occurred independently of other potentially confounding variables, including age, sex, two indices of nutritional status, season, region, and year found. Total blubber PCB levels (as Aroclor 1254) were also calculated, enabling direct comparison with a proposed threshold for adverse health effects (including immunosuppression) in marine mammals of 17 mg/kg lipid. In porpoises with total PCB levels greater than 17 mg/kg lipid (n = 154), total PCB levels were significantly higher in the infectious disease group compared to the physical trauma group (p < 0.001). This association was no longer significant in porpoises with total PCB levels of less than 17 mg/kg lipid (n = 103; p > 0.55). These findings are consistent with a causal (immunotoxic) relationship between PCB exposure and infectious disease mortality, and they provide a framework for future quantitative risk-assessment analyses of porpoise populations of known size and PCB exposure.
We recently showed that treatment with the Cu(II)-selective chelator, trientine, alleviates heart failure in diabetic rats, improves left ventricular hypertrophy in humans with type 2 diabetes, and increases urinary Cu excretion in both diabetic rats and humans compared with nondiabetic control subjects. In this study, we characterized the homeostasis of Cu and eight other nutritionally essential elements in diabetes under fully residential conditions in male subjects with type 2 diabetes and age-matched control subjects. We then probed elemental balance with oral trientine in a parallel-group, placebo-controlled study in these subjects. Before treatment, there were no detectable between-group differences in the balance of any element, although urinary output of several elements was greater in diabetic subjects. Mean extracellular superoxide dismutase (EC-SOD) activity was elevated in diabetic subjects, and its activity correlated strongly with the interaction between [Cu]serum and HbA1c. Trientine caused the Cu balance to become negative in diabetic subjects through elevated urinary Cu losses and suppressed elevated EC-SOD. Basal urinary Cu predicted urinary Cu losses during treatment, which caused extraction of systemic Cu(II). We suggest that cardiovascular complications in diabetes might be better controlled by therapeutic strategies that focus on lowering plasma glucose and loosely bound systemic Cu(II).
A group B streptococcal (GBS) bacteriophage lysin gene was cloned and expressed in Escherichia coli. The purified recombinant enzyme, calculated to have a molecular mass of 49 677 Da, lysed GBS cells. The susceptibility of GBS cells to lysis by the enzyme depended upon the growth stage at which they were harvested, with early exponential phase cells most sensitive. Calcium ions enhanced the activity of the enzyme. The enzyme also lysed other beta-haemolytic streptococci, including groups A, C, E and G streptococci, but not common oral streptococci, including Streptococcus mutans. The generation of both reducing activity and N-terminal alanine residues during lysis indicated that the lysin is a bifunctional enzyme, possessing both glycosidase and endopeptidase activities. This is consistent with the presence of two conserved sequence domains, an Acm (acetylmuramidase) domain associated with lysozyme activity, and a CHAP (cysteine, histidine-dependent amidohydrolases/peptidases) domain associated with endopeptidase activity. Site-directed mutagenesis of conserved cysteine and histidine residues in the CHAP domain and conserved aspartate and glutamate residues in the Acm domain confirmed their importance for lysozyme and endopeptidase activity respectively.
INTRODUCTION: Fever is common and difficult to control in patients with subarachnoid hemorrhage (SAH). We have previously shown an inverse relationship between fever and outcome in patients with SAH. MATERIALS/METHODS: This was a prospective, single-arm, feasibility trial in which nine patients with SAH underwent temperature management using an intravascular cooling catheter (ICC) to restore and maintain 24 hours of normothermia (36.5 degrees+/-0.2 degrees C). Enrollment occurred after development of a fever of at least 38.3 degrees C within 7 days of SAH that was refractory to acetaminophen treatment. The ICC was placed at the bedside through an introducer sheath via the femoral vein into the inferior vena cava (IVC). Portable X-ray confirmed placement. RESULTS: Normothermia was achieved in seven of the nine patients treated (78%); it was achieved in 100% of the patients with a 14F catheter (n=4) and in 60% of the patients with a 9F catheter (n=5). The two patients not reaching normothermia were not adequately treated for shivering. All other patients reached normothermia irrespective of intubation status. Overall, normothermia was well tolerated and not discontinued because of discomfort or adverse events. Two incidences of deep vein thrombosis were diagnosis by ultrasound that were not associated with clinical sequelae, and IVC filters were placed. No unanticipated adverse events occurred. DISCUSSION: We have demonstrated that fever can be safely and effectively controlled in patients with SAH for at least 24 hours using an ICC. Future studies are needed to assess the effect of such sustained therapy on outcome in patients with SAH.
Heart disease is the major cause of death in diabetes, a disorder characterized by chronic hyperglycemia and cardiovascular complications. Although altered systemic regulation of transition metals in diabetes has been the subject of previous investigation, it is not known whether changed transition metal metabolism results in heart disease in common forms of diabetes and whether metal chelation can reverse the condition. We found that administration of the Cu-selective transition metal chelator trientine to rats with streptozotocin-induced diabetes caused increased urinary Cu excretion compared with matched controls. A Cu(II)-trientine complex was demonstrated in the urine of treated rats. In diabetic animals with established heart failure, we show here for the first time that 7 weeks of oral trientine therapy significantly alleviated heart failure without lowering blood glucose, substantially improved cardiomyocyte structure, and reversed elevations in left ventricular collagen and beta(1) integrin. Oral trientine treatment also caused elevated Cu excretion in humans with type 2 diabetes, in whom 6 months of treatment caused elevated left ventricular mass to decline significantly toward normal. These data implicate accumulation of elevated loosely bound Cu in the mechanism of cardiac damage in diabetes and support the use of selective Cu chelation in the treatment of this condition.
Many pathogenic streptococci produce extracellular hyaluronan lyases which are thought to aid the spread of the organism in host tissues. In addition, several phages of group A streptococci are known to synthesize a bound form of hyaluronidase. It has been suggested that the function of this hyaluronidase is to facilitate penetration of the hyaluronan capsule by phage and thus to gain access for the phage to the cell surface of the host streptococcus [Hynes, Hancock and Ferretti (1995) Infect. Immun. 63, 3015-3020]. In the present work, the hyaluronidase of Streptococcus pyogenes bacteriophage H4489A, expressed in E. coli, has been purified and characterized. The enzyme was shown to be a lyase with a distributive action pathway. Unlike most bacterial hyaluronidases that have been characterized, the phage enzyme was found to specifically cleave hyaluronan, which adds credence to the view that its function is to digest the hyaluronan capsule of the host organism. This bacteriophage lyase may provide a practical alternative to the lyase from Streptomyces hyalurolyticus as a reagent for the specific cleavage of hyaluronan.
This article examines drug substitution with regard to hallucinogens (ayahuasca, ibogaine, peyote and LSD) set within the concept of redemption. The model examines both religious and secular approaches to the contemporary use of hallucinogens in drug substitution, both by scientists and in religious settings worldwide. The redemptive model posits that the proper use of one psychoactive substance within a spiritual or clinical context helps to free an individual from the adverse effects of their addiction to another substance and thus restores them as functioning members of their community or group. Data is drawn from the U.S., Brazil, Peru, and West Africa. Two principle mechanisms for this are proposed: the psychological mechanism of suggestibility is examined in terms of the individual reaching abstinence goals from addictive substances such as alcohol and opiates. Neurophysiological and neurochemical mechanisms to understand the efficacy of such substitution are highlighted from ongoing research on hallucinogens. Research by two of the authors with the Uñaio do Vegetal (UDV) Church in Brazil is examined in terms of the model.